Adjacent channel leakage power ratio measuring apparatus, channel power measurement apparatus method, program, and recorded medium with recorded program

ABSTRACT

The frequency of an adjacent channel signal is reduced by a down converter ( 12 ), wherein the signal (adjacent channel signal) in a predetermined band centered around the adjacent channel frequency passes through a band-pass filter ( 22 ). At this time, a signal out of the predetermined band among the signals output from the down converter ( 12 ) by the band-pass filter ( 22 ) passes through the filter ( 22 ). An FFT section ( 32 ) outputs the signal having passed through the band-pass filter ( 22 ) by making it correspond with a frequency so that a first power measuring section ( 34 ) is used for power measurement on the basis of only the signal in a predetermined band. Therefore, power on an adjacent signal is accurately measured upon reception of a measurement signal.

TECHNICAL FIELD

[0001] The present invention relates to measuring channel power.

BACKGROUND ART

[0002] Conventionally, ACLR (Adjacent Channel Leakage Power Ratio) hasbeen measured in W-CDMA system and the like. The adjacent channelleakage power ratio implies a ratio between the power of a centerchannel and the power of a predetermined adjacent channel. Usually, theadjacent channel leakage power ratio is defined as a ratio betweenpowers within predetermined bands. To obtain a power within thepredetermined band, usually, a filter is used to limit the bands, andthe power is obtained based on a signal after limiting the bands.

[0003] The following section describes how to measure the adjacentchannel leakage power ratio in the W-CDMA system. In the W-CDMA system,the adjacent channel leakage power ratio is determined as ten times of acommon logarithm (log) of a ratio between the power within a bandcentered around the center channel frequency and the power within a bandseparated from the center channel frequency by ±5 MHz or ±10 MHz. As thefilter for limiting the bands, an RRC filter (Root Raised Cosine Filter:3.84 MHz, roll off factor: 0.22) is used. The RRC filter is a filterprovides root raised cosine response. FIG. 8 shows how to measure theadjacent channel leakage power ratio according to prior art.

[0004] A signal to be measured on which the adjacent channel leakagepower ratio is measured is passed through RRC filters 110 which passsignals in predetermined bands centered around a center channelfrequency, the center channel frequency ±5 MHz, and the center channelfrequency ±10 MHz. Then, the power measuring unit 120 obtains powersP_(0M), P_(+5M), P_(−5M), P_(+10M), and P_(−10M) in the respective bandsbased on signals which have passed through the RRC filters. Then,finally, adjacent channel leakage power ratio measuring unit 130 obtainscommon logarithms (logs) of ratios between the powers of the individualadjacent channels P_(+5M), P_(−5M), P_(+10M), and P_(−10M) and the powerof the center channel P_(0M), and multiplies the logarithms by 10,thereby obtaining the adjacent channel leakage power ratios. Note thatwhen the RRC filter passes a signal in the predetermined band centeredaround the center channel frequency, the RRC filter sufficientlyattenuates a signal outside the predetermined band.

[0005] Note that measurement may be conducted while the center frequencyof the signal to be measured is moved by ±5 MHz and ±10 MHz to meet thewidened band of the signal band. In this case, the band to be measuredis lowered (down-converted) to a baseband signal.

[0006] However, when the RRC filter is used to pass a signal only in apredetermined band centered around a frequency displaced from the centerchannel frequency by a certain offset (such as 5 and 10 MHz), the RRCfilter does not sufficiently attenuate the signals other than the signalin the predetermined band. Thus, when the powers of the individualadjacent channels P_(+5M), P_(−5M), P_(+10M), and P_(−10M) are obtained,the power outside the bands of the adjacent channels are added to thepowers of the adjacent channels, the powers of the adjacent channels arenot obtained correctly. In this way, there exists such a problem thatthe power of the channel is not obtained correctly due to the inferiorcharacteristic of the band-pass filter such as the RRC filter.

[0007] Thus, the object of the present invention is to provide a channelpower measuring apparatus and the like which can precisely measure thepower of a channel such as an adjacent channel.

DISCLOSURE OF THE INVENTION

[0008] The present invention described in claim 1, is a channel powermeasuring apparatus for receiving a signal to be measured, and measuringa channel power being a power of the signal to be measured within apredetermined band, the apparatus including: a band-pass filter unit forpassing a signal which is a part of the signal to be measured within thepredetermined band; a frequency-axis-associated signal converting unitfor converting the signal to be measured after passing through theband-pass filter unit to a frequency-axis-associated signal associatedwith frequency; and a first power measuring unit for measuring the powerof the signal to be measured within the predetermined band based on asignal within the predetermined band of the frequency-axis-associatedsignal.

[0009] With the channel power measuring apparatus constituted asdescribed above, it is possible to use only the signal within thepredetermined band for the power measurement based on thefrequency-axis-associated signal even when the band-pass filter unit hasan inferior characteristic, and passes a certain quantity of a signaloutside the predetermined band. Thus, it is possible to receive thesignal to be measured, and then, to precisely measure the power withinthe predetermined band.

[0010] According to the present invention described in claim 2, thechannel power measuring apparatus according to claim 1 further includesa frequency converting unit for converting the frequency of the signalto be measured so as to supply the band-pass filter unit with theconverted signal.

[0011] According to the present invention described in claim 3, thechannel power measuring apparatus according to claim 1 further includesa frequency converting unit for converting the frequency of the signalto be measured after passing through the band-pass filter unit so as tosupply the frequency-axis-associated signal converting unit with theconverted signal.

[0012] The present invention described in claim 4, is the channel powermeasuring apparatus according to any one of claims 1 to 3, characterizedin that: the signal to be measured includes a center channel signalwithin a band determined based on a center channel frequency, and anadjacent channel signal within a band determined based on an adjacentchannel frequency separated from the center channel frequency by apredetermined frequency; and the predetermined band is a band centeredaround the adjacent channel frequency.

[0013] The present invention described in claim 5, is the channel powermeasuring apparatus according to claim 4, characterized in that thecenter channel signal and the adjacent channel signal are inputindependently.

[0014] The present invention described in claim 6, is the channel powermeasuring apparatus according to claim 4 or 5, characterized in that:the band-pass filter unit passes the adjacent channel signal and thecenter channel signal, and further including: a second power measuringunit for measuring the power of the center channel signal based on thesignal which is a part of the center channel signal, and passes throughthe band-pass filter unit.

[0015] According to the present invention described in claim 7, anadjacent channel leakage power ratio measuring apparatus includes: thechannel power measuring apparatus according to claim 6; and an adjacentchannel leakage power ratio measuring unit for measuring the adjacentchannel leakage power ratio based on the ratio between the measuredresult of the first power measuring unit and the measured result of thesecond power measuring unit.

[0016] The band-pass filter unit may present a degraded characteristicin terms of passing the adjacent channel signal when it is constitutedto pass the center channel signal. In this case, as for the adjacentchannel signal, it is possible to precisely measure the power within theadjacent channel by measuring the power within the adjacent channelbased on the frequency-axis-associated signal.

[0017] Then, as for the center channel signal, the power within thecenter channel is precisely measured by using the signal after passingthrough the band-pass filter unit to measure the power.

[0018] Thus, since the power within the adjacent channel and the powerwithin the center channel are precisely measured, the adjacent channelleakage power ratio is precisely measured.

[0019] The present invention described in claim 8, is a channel powermeasuring method for receiving a signal to be measured, and measuring achannel power being a power of the signal to be measured within apredetermined band, the method including: a band-pass filter step forpassing a signal which is a part of the signal to be measured within thepredetermined band; a frequency-axis-associated signal converting stepfor converting the signal to be measured after performing the band-passfilter step to a frequency-axis-associated signal associated withfrequency; and a first power measuring step for measuring the power ofthe signal to be measured within the predetermined band based on asignal within the predetermined band of the frequency-axis-associatedsignal.

[0020] The present invention described in claim 9, is a program ofinstructions for execution by the computer to perform a channel powermeasuring process for receiving a signal to be measured, and measuring achannel power being a power of the signal to be measured within apredetermined band, the process including: a band-pass filter processingfor passing a signal which is a part of the signal to be measured withinthe predetermined band; a frequency-axis-associated signal convertingprocessing for converting the signal to be measured after performing theband-pass filter processing to a frequency-axis-associated signalassociated with frequency; and a first power measuring processing formeasuring the power of the signal to be measured within thepredetermined band based on a signal within the predetermined band ofthe frequency-axis-associated signal.

[0021] The present invention described in claim 10, is a program ofinstructions for execution by the computer to perform a channel powermeasuring process for a channel power measuring apparatus for receivinga signal to be measured, and measuring a channel power being a power ofthe signal to be measured within a predetermined band, the apparatusincluding a band-pass filter unit for passing a signal which is a partof the signal to be measured within the predetermined band, the processincluding: a frequency-axis-associated signal converting processing forconverting the signal to be measured after performing the band-passfilter processing to a frequency-axis-associated signal associated withfrequency; and a first power measuring processing for measuring thepower of the signal to be measured within the predetermined band basedon a signal within the predetermined band of thefrequency-axis-associated signal.

[0022] The present invention described in claim 11, is acomputer-readable medium having a program of instructions for executionby the computer to perform a channel power measuring process forreceiving a signal to be measured, and measuring a channel power being apower of the signal to be measured within a predetermined band, theprocess including: a band-pass filter processing for passing a signalwhich is a part of the signal to be measured within the predeterminedband; a frequency-axis-associated signal converting processing forconverting the signal to be measured after performing the band-passfilter processing to a frequency-axis-associated signal associated withfrequency; and a first power measuring processing for measuring thepower of the signal to be measured within the predetermined band basedon a signal within the predetermined band of thefrequency-axis-associated signal.

[0023] The present invention described in claim 12, is acomputer-readable medium having a program of instructions for executionby the computer to perform a channel power measuring process for achannel power measuring apparatus for receiving a signal to be measured,and measuring a channel power being a power of the signal to be measuredwithin a predetermined band, the apparatus including a band-pass filterunit for passing a signal which is a part of the signal to be measuredwithin the predetermined band, the process including: afrequency-axis-associated signal converting processing for convertingthe signal to be measured after performing the band-pass filterprocessing to a frequency-axis-associated signal associated withfrequency; and a first power measuring processing for measuring thepower of the signal to be measured within the predetermined band basedon a signal within the predetermined band of thefrequency-axis-associated signal.

BRIEF DESCRIPTION OF THE DRAWINGS

[0024]FIG. 1 is a block diagram showing the constitution of an adjacentchannel leakage power ratio measuring apparatus 1 according to a firstembodiment of the present invention;

[0025]FIG. 2 includes drawings showing spectra of signals to bemeasured, and a spectrum of an adjacent channel signal (FIG. 2(a)) and aspectrum of a center channel signal (FIG. 2(b)) are shown;

[0026]FIG. 3 includes drawings showing spectra of signals after passingthrough a band-pass filter 22, and a spectrum of the adjacent channelsignal after passing through the band-pass filter 22 (FIG. 3(a)) and aspectrum of the center channel signal after passing through theband-pass filter 22 (FIG. 3(b)) are shown;

[0027]FIG. 4 shows a result when an FFT unit 32 applies FFT to theadjacent channel signal;

[0028]FIG. 5 is a block diagram showing the constitution of the adjacentchannel leakage power ratio measuring apparatus 1 according to a secondembodiment of the present invention;

[0029]FIG. 6 is a block diagram showing the constitution of the adjacentchannel leakage power ratio measuring apparatus 1 according to a thirdembodiment of the present invention;

[0030]FIG. 7 is a block diagram showing the constitution of the adjacentchannel leakage power ratio measuring apparatus 1 according to a fourthembodiment of the present invention; and

[0031]FIG. 8 shows how to measure the adjacent channel leakage powerratio according to prior art.

BEST MODE FOR CARRYING OUT THE INVENTION

[0032] The following section describes embodiments of the presentinvention while referring to drawings.

First Embodiment

[0033]FIG. 1 is a block diagram showing the constitution of an adjacentchannel leakage power ratio measuring apparatus 1 according to a firstembodiment of the present invention. The adjacent channel leakage powerratio measuring apparatus 1 according to the first embodiment of thepresent invention includes down-converters (frequency converting means)12 and 14, a band-pass filter 22, an FFT (Fast Fourier Transfer) unit(frequency-axis-associated signal converting means) 32, a first powermeasuring unit 34, a second power measuring unit 40, and an adjacentchannel leakage power ratio measuring unit 50. Note that thedown-converter (frequency converting means) 12, the band-pass filter 22,the FFT (Fast Fourier Transfer) unit (frequency-axis-associated signalconverting means) 32, and the first power measuring unit 34 constitute achannel power measuring apparatus 2 which is a characteristic part ofthe present invention. The channel power measuring apparatus 2 measuresthe power of the adjacent channel.

[0034] The adjacent channel leakage power ratio measuring apparatus 1 isan apparatus which receives signals to be measured, and then, measuresthe adjacent channel leakage power ratio. As the signals to be measured,signals according to W-CDMA (Wide band Code Division Multiple Access)system are assumed. The signals to be measured include two types, whichare a center channel signal and an adjacent channel signal, and arerespectively supplied for the adjacent channel leakage power ratiomeasuring apparatus 1. The center channel signal is a signal within aband centered around a center channel frequency. The adjacent channelsignal is a signal within a band centered around an adjacent channelfrequency separated from the center channel frequency by a certainfrequency. In the first embodiment, it is assumed that the adjacentchannel frequency=center channel frequency−5 [MHz]. The band width ofthe center channel signal and the adjacent channel signal is determinedby the characteristic of the band-pass filter 22, and is detailed later.

[0035] Though FIG. 1 shows only one adjacent channel signal, multipleadjacent channel signals may exist. For example, the adjacent channelfrequency=the center channel frequecy+5 [MHz] or the adjacent channelfrequencies=the center channel frequency+10 [MHz], and may beadditionally supplied for the adjacent channel leakage power ratiomeasuring apparatus 1.

[0036] The down converters (frequency converting means) 12 and 14convert the signals to be measured so as to reduce their frequencies,thereby forming baseband signals. The down converter 12 reduces thefrequency of the adjacent channel signal, and the down converter 14reduces the frequency of the center channel signal. It is assumed thatthe IF frequency of the down converter 12 is 5 MHz, and the IF frequencyof the down converter 14 is 10 MHz. The frequencies are reduced asexpressed by equations (1) and (2) where the adjacent channel signal isSadj and the center channel signal is Scen. Note that the equation (1)indicates the frequency reduction by the down converter 12, and theequation (2) indicates the frequency reduction by the down converter 14.

Sadj·cos(2π(10 MHz) t)−j·Sadj·sin(2π(10 MHz)t)   (1)

Scen·cos(2π(10 MHz) t)−j·Scen·sin(2π(10 MHz)t)   (2)

[0037] The band-pass filter 22 passes the signals to be measured afterpassing through the down converters 12 and 14. The band-pass filter 22is an RRC (Root Raised Cosine) filer which provides root raised cosineresponse, for example. The band-pass filter 22 is set so as to pass thesignals within the bands of the baseband signals of the down-converters12 and 14. When the band-pass filter 22 is an RRC filter (3.84 MHz, rolloff factor: 0.22), the predetermined band extends from [10 MHz−used bandW] to [10 MHz+used band W]. Note that, used bandW=(1+0.22)×3.84/2=2.3424 [MHz]. Therefore, the band-pass filter 22passes a part from 10−2.3424 [MHz] to 10+2.3424 [MHz] of the signalhaving passed through the down-converter 12. Also, the band-pass filter22 passes a signal which is a part from 10−2.3424 [MHz] to 10+2.3424[MHz] of the signal having passed through the down-converter 14.

[0038] The band-pass filter 22 is set so as to have an excellentcharacteristic only for passing a signal within the band centered around10 [MHz]. Thus, the characteristic of passing a signal within the bandcentered around 5 [MHz] degrades. Namely, it also passes a part outsidethe predetermined band centered around 5 [MHz] of the signal output fromthe down converter 12.

[0039] The FFT (Fast Fourier Transfer) unit (frequency-axis-associatedsignal converting means) 32 applies FFT (Fast Fourier Transfer) to thesignal which is the part of the adjacent channel signal output from thedown converter 12, and passes through the band-pass filter 22. As aresult, the signal input to the FFT unit 32 is output as a signalassociated with the frequency. The signal output from the FFT unit 32 isreferred to as a frequency-axis-associated signal. Thefrequency-axis-associated signal implies a signal associated with thefrequency while the frequency is assigned to an axis. A unit whichoutputs the frequency-axis-associated signal may be used in place of theFFT unit 32.

[0040] A fixed point operation unit may be used as the FFT unit 32. Thepower corresponding to the center channel is attenuated since the signalinput to the FFT unit 32 is the signal which is output from the downconverter 12, and then passes through the band-pass filter 22. Thus, thepower of the signal input to the FFT unit 32 is close to the power ofthe adjacent channel. Therefore, it is possible to reduce thecalculation error by shifting the input level of the FFT unit 32 to anoptimal level for the fixed point operation unit.

[0041] The first power measuring unit 34 measures the power Padj of thesignal to be measured within the predetermined band (adjacent channelsignal) based on the part within the band centered around the adjacentchannel frequency (from 10−2.3424 [MHz] to 10+2.3424 [MHz]) of thefrequency-axis-associated signal. Equation (3) shows how to measure thepower Padj.

[Equation 3]

[0042] $\begin{matrix}{P_{a\quad {dj}} = {\sum\limits_{k = 1}^{N}{\left( {{FFT}_{{Re}_{k}^{2}} + {FFT}_{{Im}_{k}^{2}}} \right)/N}}} & (3)\end{matrix}$

[0043] Note that FFT_(Re) is the real part of thefrequency-axis-associated signal, FFT_(Im) is an imaginary part of thefrequency-axis-associated signal, and N is the number of data within theband centered around the adjacent channel frequency.

[0044] The second power measuring unit 40 measures the power Pcen of thecenter channel signal based on the signal which is a part of the centerchannel signal output from the down converter 14, and passes through theband-pass filter 22. Equation (4) shows how to measure the power Pcen.

[Equation 4]

[0045] $\begin{matrix}{P_{cen} = {\sum\limits_{k = 1}^{N}{\left( {{BB}_{{Re}_{k}^{2}} + {BB}_{{Im}_{k}^{2}}} \right)/N}}} & (4)\end{matrix}$

[0046] Note that BB_(Re) is a real part of the signal which is a part ofthe center channel signal output from the down-converter 14 and passesthrough the band-pass filter 22, BB_(Im) is an imaginary part of thesignal which is a part of the center channel signal output from thedown-converter 14 and passes through the band-pass filter 22, and N isthe number of data within the band centered around the center channelfrequency.

[0047] The adjacent channel leakage power ratio measuring unit 50measures the adjacent channel leakage power ratio based on the measuredresult Padj from the first power measuring unit 34 and the measuredresult Pcen from the second power measuring unit 40. Note that theadjacent channel leakage power ratio=10 log(Padj/Pcen).

[0048] Note that with the down-converter 12, the band-pass filter 22,the FFT unit 32, and the first power measuring unit 34, the adjacentchannel power is precisely measured though the characteristic of theband-pass filter 22 is inferior in the adjacent channel (from 5−2.3424[MHz] to 5+2.3424 [MHz]). Namely, the down-converter 12, the band-passfilter 22, the FFT unit 32, and the first power measuring unit 34constitute the channel power measuring apparatus 2 which overcomes theinferior characteristic of the band-pass filter 22.

[0049] The following section describes the operation of the firstembodiment of the present invention.

[0050] Referring to FIG. 1, the adjacent channel signal and the centerchannel signal of the signals to be measured are independently suppliedfor the adjacent channel leakage power ratio measuring apparatus 1. Inmore detail, the adjacent channel signal is supplied for thedown-converter 12, and the center channel signal is supplied for thedown-converter 14. Note that the IF frequency is 5 MHz in thedown-converter 12, and the IF frequency is 10 MHz in the down-converter14. FIG. 2(a) shows the spectrum of the adjacent channel signal, andFIG. 2(b) shows the spectrum of the center channel signal.

[0051] The frequency of the adjacent channel signal is reduced to abaseband signal by the down-converter 12, and the frequency of thecenter channel signal is reduced to a baseband signal by thedown-converter 14. The baseband signals are provided for the band-passfilter 22, and the signals within the predetermined band pass throughthe band-pass filter 22. In more detail, of the baseband signal, thesignal which is the part from 10−2.3424 [MHz] to 10+2.3424 [MHz] of theadjacent channel signal output from the down-converter 12 passes throughthe band-pass filter 22. Of the baseband signal, the signal which is thepart from 10−2.3424 [MHz] to 10+2.3424 [MHz] of the center channelsignal output from the down-converter 14 passes through the band-passfilter 22.

[0052]FIG. 3(a) shows the spectrum of a signal which is the adjacentchannel signal output from the down-converter 12, and passes through theband-pass filter 22, and FIG. 3(b) shows the spectrum of a signal whichis the center channel signal output from the down-converter 14, andpasses through the band-pass filter 22. Referring to FIG. 3(a), it canbe observed that leakage components S2 and S3, which the band-passfilter 22 passes though it should not, exist in addition to the actualadjacent channel signal S1. As a result, it can be understood that theadjacent channel signal has a large error. Referring to FIG. 3(b), thesignal is large around 0 MHz, and decreases from a neighborhood of apoint separated by approximately 2.3 MHz (used band W). As a result, itcan be observed that the center channel signal has a small error.

[0053] Of course, the band-pass filter 22 simply limits the band, anddoes not have a feature of representing a signal as a spectrum.Therefore, even when the signal after passing through the band-passfilter 22 is simply observed, it is not possible to recognize how mucherror the adjacent channel signal contains. Thus, when the signal afterpassing through the band-pass filter 22 is simply used to measure thepower of the adjacent channel signal, the error is large and cannot beremoved.

[0054] The signal which is the adjacent channel signal output from thedown converter 12, and passes through the band-pass filter 22 is inputto the FFT unit 32. The FFT unit 32 applies FFT on the input signal.FIG. 4 shows a result when the FFT unit 32 applies FFT to the adjacentchannel signal. FIG. 4 is similar to FIG. 3(a). However, FIG. 4 showsthe used band width (2W). The signal inside the used band width is theactual adjacent channel signal. According to the output result from theFFT unit 32, it is possible to recognize which part of the signal afterpassing through the band-pass filter 22 is the actual adjacent channelsignal.

[0055] Based on the output from the FFT unit 32, the first powermeasuring unit 34 measures the power Padj of the adjacent channelsignal. Since it is possible to recognize which part of the signal afterpassing through the band-pass filter 22 is the actual adjacent channelsignal according to the output result from the FFT unit 32, the firstpower measuring unit 34 precisely measures the Padj.

[0056] On the other hand, the signal which is the center channel signaloutput from the down converter 14, and passes through the band-passfilter 22 is input to the second power measuring unit 40. The signalwhich is the center channel signal after passing through the band-passfilter 22 has a small error as shown in FIG. 3(b). Thus, the signalwhich is the center channel signal after passing through the band-passfilter 22 can be directly used for measuring the power of the centerchannel signal without converting it into a signal associated with thefrequency axis. The second power measuring unit 40 measures the powerPcen of the center channel signal based on the signal which is thecenter channel signal after passing through the band-pass filter 22.

[0057] The power Padj of the adjacent channel signal measured by thefirst power measuring unit 34, and the power Pcen of the center channelsignal measured by the second power measuring unit 40 are supplied forthe adjacent channel leakage power ratio measuring unit 50. The adjacentchannel leakage power ratio measuring unit 50 measures the adjacentchannel leakage power ratio.

[0058] With the first embodiment, even when the band-pass filter 22 hasan degraded characteristic, and passes a certain quantity of a signaloutside the band of the adjacent channel signal, only the signal withinthe band of the adjacent channel signal is used for measuring the powerof the adjacent channel signal based on the frequency-axis-associatedsignal output from the FFT unit 32. Thus, it is possible to receive thesignal to be measured, and then to precisely measure the power withinthe predetermined band (band of the adjacent channel signal).

[0059] Note that to precisely measure the power within the predeterminedband (band of the adjacent channel signal), though it is conceivable toimprove the characteristic of the band-pass filter 22, the number oftaps increases and the time required for calculation increases in caseof a software filter. Also, a high-order filter is required, and thesize of the circuit increases in case of a hardware filter.

[0060] However, with the first embodiment, since it is possible toprecisely measure the power within the predetermined band (band of theadjacent channel signal) without improving the characteristic of theband-pass filter 22, it does not cause the increase of the calculationtime, or the increase of the circuit size.

[0061] Also, the band-pass filter 22 may present a degradedcharacteristic for passing the adjacent channel signal when it isconstituted to pass the center channel signal. In this case, as for theadjacent channel signal, it is possible to precisely measure the powerPadj within the adjacent channel by using the first power measuring unit34 to measure the power within the adjacent channel based on thefrequency-axis-associated signal.

[0062] Then, as for the center channel signal, the power Pcen within thecenter channel is precisely measured by using the second power measuringunit 40 to measure the power based on the signal having passed throughthe band-pass filter 22.

[0063] Thus, since the power Padj within the adjacent channel and thepower Pcen within the center channel are precisely measured, theadjacent channel leakage power ratio is precisely measured.

Second Embodiment

[0064] The adjacent channel leakage power ratio measuring apparatus 1according to a second embodiment differs from the first embodiment inthat the band-pass filter 22 is disposed on the upstream side of thedown converters 12 and 14.

[0065]FIG. 5 shows the constitution of the adjacent channel leakagepower ratio measuring apparatus 1 according to the second embodiment.Parts similar to those in the first embodiment are assigned with thesame number, and description for them is not provided. The band-passfilter 22 is a hardware filter, for example. The band-pass filter 22passes the signals to be measured. As for the center channel signal, theband-pass filter 22 passes the signal within the predetermined bandcentered around the center channel frequency. As for the adjacentchannel signal, the band-pass filter 22 passes the signal within thepredetermined band centered around the adjacent channel frequency. Howto obtain the predetermined band is similar to that in the firstembodiment.

[0066] The band-pass filter 22 is set so as to have an excellentcharacteristic of passing a signal within the predetermined bandcentered around the center channel frequency. However, as a result, thecharacteristic of passing a signal in the band centered around theadjacent channel frequency degrades. Namely, the band-pass filter 22passes a signal outside the predetermined band centered around theadjacent channel frequency.

[0067] The down-converter 12 reduces the frequency of the adjacentchannel signal having passed through the band-pass filter 22, andsupplies the FFT unit 32 with the signal as a baseband signal. Thedown-converter 14 reduces the frequency of the center channel signalhaving passed through the band-pass filter 22, and supplies the secondpower measuring unit 40 with the signal as a baseband signal. Note thatit is assumed that-the IF frequency of the down converter 12 is 5 MHz,and the IF frequency of the down converter 14 is 10 MHz. Equations forreducing the frequency are similar to those in the first embodiment.

[0068] The FFT unit 32, the first power measuring unit 34, the secondpower measuring unit 40, and the adjacent channel leakage power ratiomeasuring unit 50 are similar to those in the first embodiment.

[0069] The following section describes the operation of the secondembodiment.

[0070] Referring to FIG. 5 first, the adjacent channel signal and thecenter channel signal of the signals to be measured are independentlysupplied for the band-pass filter 22 of the adjacent channel leakagepower ratio measuring apparatus 1. The spectrum of the adjacent channelsignal is the same as that in FIG. 2(a), and the spectrum of the centerchannel signal is the same as that in FIG. 2(b).

[0071] The down converter 12 reduces the frequency of a signal which isa part of the adjacent channel signal having passed through theband-pass filter 22 (signal from [adjacent channel frequency−used bandW] to [adjacent channel frequency+used band W]), thereby converting intothe baseband signal. The down converter 14 reduces the frequency of asignal which is a part of the center channel signal having passedthrough the band-pass filter 22 (signal from [center channelfrequency−used band W] to [center channel frequency+used band W]),thereby converting into the baseband signal.

[0072] The spectrum of the signal output from the down converter 12 issimilar to that in FIG. 3(a), and the spectrum of the signal output fromthe down converter 14 is similar to that in FIG. 3(b).

[0073] The rest of the operation is similar to that in the firstembodiment.

[0074] With the second embodiment, effects similar to those of the firstembodiment are provided. Third embodiment The adjacent channel leakagepower ratio measuring apparatus 1 according to a third embodimentdiffers from the first embodiment in that the center channel signal andthe adjacent channel signal are combined.

[0075]FIG. 6 shows the constitution of the adjacent channel leakagepower ratio measuring apparatus 1 according to the third embodiment. Thesignals to be measured include two types, which are the center channelsignal and the adjacent channel signal, and are supplied in a combinedform for the adjacent channel leakage power ratio measuring apparatus 1.The rest of the constitution and the operation are similar to those inthe first embodiment.

[0076] With the third embodiment, effects similar to those of the firstembodiment are also provided.

Fourth Embodiment

[0077] The adjacent channel leakage power ratio measuring apparatus 1according to a fourth embodiment differs from the third embodiment inthat the down converters 12 and 14 are not provided.

[0078]FIG. 7 shows the constitution of the adjacent channel leakagepower ratio measuring apparatus 1 according to the fourth embodiment.The signals to be measured include two types, which are the centerchannel signal and the adjacent channel signal, and are supplied in acombined form for the band-pass filter 22 of the adjacent channelleakage power ratio measuring apparatus 1. The rest of the constitutionand the operation are similar to those in the first embodiment.

[0079] With the fourth embodiment, effects similar to those of the firstembodiment are also provided.

[0080] The embodiments described above are realized in the followingway. A computer includes a CPU, a hard disk, and a medium (such as afloppy (registered trade mark) disk, and a CD-ROM) reading apparatus, amedia recording a program realizing the aforementioned individual parts(such as the FFT unit 32 and the first power measuring unit 34) is readby the media reading apparatus, and the program is installed on the harddisk. The aforementioned functions are realized in this way too.

[0081] With the present invention, it is possible to use only the signalwithin the predetermined band for the power measurement based on thefrequency-axis-associated signal even when the band-pass filter meanshas an inferior characteristic, and passes a certain quantity of asignal outside the predetermined band. Thus, it is possible to receivethe signals to be measured, and then, to precisely measure the powerswithin the predetermined bands.

1. A channel power measuring apparatus for receiving a signal to bemeasured, and measuring a channel power being a power of said signal tobe measured within a predetermined band, the apparatus comprising: aband-pass filter means for passing a signal which is a part of saidsignal to be measured within said predetermined band; afrequency-axis-associated signal converting means for converting saidsignal to be measured after passing through said band-pass filter meansto a frequency-axis-associated signal associated with frequency; and afirst power measuring means for measuring the power of said signal to bemeasured within said predetermined band based on a signal within thepredetermined band of said frequency-axis-associated signal.
 2. Thechannel power measuring apparatus according to claim 1 furthercomprising a frequency converting means for converting the frequency ofsaid signal to be measured so as to supply said band-pass filter meanswith the converted signal.
 3. The channel power measuring apparatusaccording to claim 1 further comprising a frequency converting means forconverting the frequency of said signal to be measured after passingthrough said band-pass filter means so as to supply saidfrequency-axis-associated signal converting means with the convertedsignal.
 4. The channel power measuring apparatus according to any one ofclaims 1 to 3, characterized in that: said signal to be measuredincludes a center channel signal within a band determined based on acenter channel frequency, and an adjacent channel signal within a banddetermined based on an adjacent channel frequency separated from thecenter channel frequency by a predetermined frequency; and saidpredetermined band is a band centered around the adjacent channelfrequency.
 5. The channel power measuring apparatus according to claim4, characterized in that said center channel signal and said adjacentchannel signal are input independently.
 6. The channel power measuringapparatus according to claim 4 or 5, characterized in that: saidband-pass filter means passes said adjacent channel signal and saidcenter channel signal, and further comprising: a second power measuringmeans for measuring the power of said center channel signal based on thesignal which is a part of the center channel signal, and passes throughsaid band-pass filter means.
 7. An adjacent channel leakage power ratiomeasuring apparatus comprising: the channel power measuring apparatusaccording to claim 6; and an adjacent channel leakage power ratiomeasuring means for measuring the adjacent channel leakage power ratiobased on the ratio between the measured result of said first powermeasuring means and the measured result of said second power measuringmeans.
 8. A channel power measuring method for receiving a signal to bemeasured, and measuring a channel power being a power of said signal tobe measured within a predetermined band, the method comprising: aband-pass filter step for passing a signal which is a part of saidsignal to be measured within said predetermined band; afrequency-axis-associated signal converting step for converting saidsignal to be measured after performing said band-pass filter step to afrequency-axis-associated signal associated with frequency; and a firstpower measuring step for measuring the power of said signal to bemeasured within said predetermined band based on a signal within thepredetermined band of said frequency-axis-associated signal.
 9. Aprogram of instructions for execution by the computer to perform achannel power measuring process for receiving a signal to be measured,and measuring a channel power being a power of said signal to bemeasured within a predetermined band, the process comprising: aband-pass filter processing for passing a signal which is a part of saidsignal to be measured within said predetermined band; afrequency-axis-associated signal converting processing for convertingsaid signal to be measured after performing said band-pass filterprocessing to a frequency-axis-associated signal associated withfrequency; and a first power measuring processing for measuring thepower of said signal to be measured within said predetermined band basedon a signal within the predetermined band of saidfrequency-axis-associated signal.
 10. A program of instructions forexecution by the computer to perform a channel power measuring processfor a channel power measuring apparatus for receiving a signal to bemeasured, and measuring a channel power being a power of said signal tobe measured within a predetermined band, the apparatus including aband-pass filter means for passing a signal which is a part of saidsignal to be measured within said predetermined band, the processcomprising: a frequency-axis-associated signal converting processing forconverting said signal to be measured after performing said band-passfilter processing to a frequency-axis-associated signal associated withfrequency; and a first power measuring processing for measuring thepower of said signal to be measured within said predetermined band basedon a signal within the predetermined band of saidfrequency-axis-associated signal.
 11. A computer-readable medium havinga program of instructions for execution by the computer to perform achannel power measuring process for receiving a signal to be measured,and measuring a channel power being a power of said signal to bemeasured within a predetermined band, the process comprising: aband-pass filter processing for passing a signal which is a part of saidsignal to be measured within said predetermined band; afrequency-axis-associated signal converting processing for convertingsaid signal to be measured after performing said band-pass filterprocessing to a frequency-axis-associated signal associated withfrequency; and a first power measuring processing for measuring thepower of said signal to be measured within said predetermined band basedon a signal within the predetermined band of saidfrequency-axis-associated signal.
 12. A computer-readable medium havinga program of instructions for execution by the computer to perform achannel power measuring process for a channel power measuring apparatusfor receiving a signal to be measured, and measuring a channel powerbeing a power of said signal to be measured within a predetermined band,the apparatus including a band-pass filter means for passing a signalwhich is a part of said signal to be measured within said predeterminedband, the process comprising: a frequency-axis-associated signalconverting processing for converting said signal to be measured afterperforming said band-pass filter processing to afrequency-axis-associated signal associated with frequency; and a firstpower measuring processing for measuring the power of said signal to bemeasured within said predetermined band based on a signal within thepredetermined band of said frequency-axis-associated signal.